This invention relates generally to mechanical seals. More particularly, the present invention relates to universal split mechanical seals that provide strong sealing capabilities under different operating conditions.
Split mechanical seals with resiliently mounted faces are employed in a wide variety of mechanical apparatuses to provide a pressure-tight and fluid-tight seal. The mechanical seal is usually positioned about a rotating shaft that is mounted in and protruding from a stationary housing. The seal is usually bolted to the housing at the shaft exit, thus preventing the loss of pressurized process fluid from the housing. Conventional split mechanical seals include face type mechanical seals, which include a pair of sealing rings that are concentrically disposed about the shaft, and axially spaced from each other. The sealing rings each have sealing faces that are biased into sealing contact with each other. Usually, one seal ring remains stationary, while the other ring contacts the shaft and rotates therewith. The mechanical seal prevents leakage of the pressurized process fluid to the external environment by biasing the seal ring sealing faces in sealing contact with each other. The rotary seal ring is usually mounted in a holder assembly which is disposed in a chamber formed by a gland assembly. The holder assembly has a pair of holder halves secured together by a screw. Likewise, the gland assembly has a pair of gland halves also secured together by a screw. The sealing rings are often divided into segments, each segment having a pair of sealing faces, thereby resulting in each ring being a split ring that can be mounted about the shall without the necessity of freeing one end of the shaft ends.
A drawback of the conventional split mechanical seal with resiliently mounted faces is that the sealing capability of the seal rings degrades when the ambient pressure becomes greater than the pressure of the process fluid. This degradation occurs since an outward radial force develops on the seal rings, separating the split seal ring segments and allowing pressurized fluid to escape to the external environment.
Another drawback of conventional split seals is that the screws which secure the gland and holder segments together are usually mounted in predetermined tapholes, which typically necessitate rotating the shaft after securing one screw, to affix the other screws. Additionally, during disassembly of the mechanical seal, the screws can become disengaged from either segment of the gland and holder, thereby increasing the likelihood that the screws can become detached and damage other components of the housing, or lost.
As the above described and other prior art sealing systems have proven less than optimal, an object of this invention is to provide an improved mechanical seal that provides a fluid-tight seal under a variety of operating pressure conditions.
Another object of the invention is to provide a single split mechanical seal that can function under different operating pressures, thereby eliminating the need for employing different seals.
Still another object of the invention is to provide a split mechanical seal that is relatively easy to assemble and to disassemble.
Other general and more specific objects of this invention will in part be obvious and will in part be evident from the drawings and the description which follow.